In Quiver Function Error: " index must be a positive integer or logical."

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Daniel 2013-8-13

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采纳的回答： Sajid Khan

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Hey,

I get the error

??? Attempted to access quiver(2.76604,2.17365,-0.123257,0.81116); index must be a positive integer or logical.

and can't imagine why, because if I type quiver(2.76604,2.17365,-0.123257,0.81116) in the Command Window it works well.

Here is the Code:

      for k=1:n
          for l=1:n
              if E(k,l) >= 1
                  x1=2+cos(2*pi/n*k); x2=2+cos(2*pi/n*l); y1=2+sin(2*pi/n*k); y2=2+sin(2*pi/n*l);
                  u=y1-x1; v=y2-x2;
                  quiver(x1,x2,u,v);%,'Color',color,'LineWidth',2);
              end
          end
      end

with n=length(E) and E(i,j) = 1 if there excists an arrow between i and j

Thank You Daniel

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Daniel 2013-8-13

Hmm this is weird because if I run exactly your modification of the code I get the error:

??? Attempted to access quiver(1.5,1.5,1.36603,1.36603); index must be a positive integer or logical.

Error in paintgraph at 23

quiver(x1,x2,u,v);

I can't imagine why. Yes the code I presented yields the error.

Daniel 2013-8-13

Got the solution. I accidantly set quiver=1 earlier.

Thank you very much.

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采纳的回答

Sajid Khan 2013-8-13

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https://ww2.mathworks.cn/matlabcentral/answers/84634-in-quiver-function-error-index-must-be-a-positive-integer-or-logical#answer_94198

use clear all before executing your code.

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